linux-kernel - Re: [PATCH v2] mm: page_alloc: Add debug log in free_reserved

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Message-ID: <7027fa91-296f-01cb-6c5d-d25c81c835d5@redhat.com>
Date:   Mon, 11 Oct 2021 10:34:39 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Faiyaz Mohammed <quic_faiyazm@...eaurora.org>,
        akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     guptap@...eaurora.org, Faiyaz Mohammed <faiyazm@...eaurora.org>
Subject: Re: [PATCH v2] mm: page_alloc: Add debug log in free_reserved_area
 for static memory

On 11.10.21 09:11, Faiyaz Mohammed wrote:
> From: Faiyaz Mohammed <faiyazm@...eaurora.org>
> 
> For INITRD and initmem memory is reserved through "memblock_reserve"
> during boot up but it is free via "free_reserved_area" instead
> of "memblock_free".
> For example:
> [    0.294848] Freeing initrd memory: 12K.
> [    0.696688] Freeing unused kernel memory: 4096K.
> 
> To get the start and end address of the above freed memory and to account
> proper memblock added pr_debug log in "free_reserved_area".
> After adding log:
> [    0.294837] 0x00000083600000-0x00000083603000 free_initrd_mem+0x20/0x28
> [    0.294848] Freeing initrd memory: 12K.
> [    0.695246] 0x00000081600000-0x00000081a00000 free_initmem+0x70/0xc8
> [    0.696688] Freeing unused kernel memory: 4096K.
> 
> Signed-off-by: Faiyaz Mohammed <faiyazm@...eaurora.org>
> ---
> changes in v2:
> 	- To avoid confusion, remove the memblock_dbg print and drop the
> 	memblock_free string, now using pr_debug to print the address ranges.
> 
>   mm/page_alloc.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 668edb1..395df3f 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -8153,6 +8153,11 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
>   	if (pages && s)
>   		pr_info("Freeing %s memory: %ldK\n", s, K(pages));
>   
> +#ifdef CONFIG_HAVE_MEMBLOCK
> +		pr_debug("%#016llx-%#016llx %pS\n",
> +			__pa(start), __pa(end), (void *)_RET_IP_);
> +#endif
> +

Are we missing parentheses that the code indentation implies?
Further, I think we want to use "%pa" instead of "%llx" and
eventually drop the CONFIG_HAVE_MEMBLOCK dependency. Maybe

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b37435c274cf..e7946e5ca094 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8097,6 +8097,8 @@ EXPORT_SYMBOL(adjust_managed_page_count);
  
  unsigned long free_reserved_area(void *start, void *end, int poison, const char *s)
  {
+       const phys_addr_t pstart = __pa(start);
+       const phys_addr_t pend = __pa(end);
         void *pos;
         unsigned long pages = 0;
  
@@ -8125,9 +8127,11 @@ unsigned long free_reserved_area(void *start, void *end, int poison, const char
                 free_reserved_page(page);
         }
  
-       if (pages && s)
+       if (pages && s) {
                 pr_info("Freeing %s memory: %ldK\n",
                         s, pages << (PAGE_SHIFT - 10));
+               pr_debug("[%pa-%pa] %pS\n", &pstart, &pend, (void *)_RET_IP_);
+       }
  
         return pages;
  }



-- 
Thanks,

David / dhildenb